In a mobile communication system, a User Equipment (UE) performs a radio network deployment state test process for collecting logs for radio network deployment state information such as radio link failure occurrence, signal strength of a signal which is transmitted to/received from a radio communication network, and the like during a predetermined period in order to test radio network deployment state.
The description of the radio network deployment state test process will be described with reference to an Evolved Packet System (EPS) as a typical example of a mobile communication system that has been proposed up to now.
In the EPS, a radio network deployment state test process for testing radio network deployment state such as coverage of a radio link and radio link failure occurrence uses a Minimization of Drive Test (MDT) scheme, and the description of the MDT scheme will be followed.
The MDT scheme represents a radio network deployment state test scheme which uses User Equipments (UEs) receiving a communication service in a field in order to prevent occurrence of shadow areas and optimize establishment location of enhanced Node Bs (eNBs) on a radio network deployment.
The MDT scheme includes two schemes, i.e., an immediate MDT scheme and a logged MDT scheme according to operation modes of a UE. The immediate MDT scheme is an MDT scheme which is performed if an operation mode of the UE is a connected mode, and the logged MDT scheme is an MDT scheme which is performed if an operation mode of the UE is an idle mode.
The mobile communication system should transmit MDT configuration information indicating a period (or duration), an interval, and a region where the eNB should collect radio network deployment state information to the UE. If the immediate MDT scheme is used as the radio network deployment state test scheme, for example, the MDT configuration information is transmitted to the UE operating in the connected mode using a Radio Resource Control (RRC) Reconfiguration message. If the logged MDT scheme is used as the radio network deployment state test scheme, for example, the MDT configuration information is transmitted to the UE operating in the idle mode using a Logged Measurement Configuration message.
Upon operating in the connected mode, the UE receives the MDT configuration information through the RRC Reconfiguration message. Alternatively, the UE receives the MDT configuration information through the Logged Measurement Configuration message upon operating in the idle mode. After receiving the MDT configuration information, the UE sets a registered Public Land Mobile Network (PLMN) in which the UE is registered as an MDT_PLMN. The MDT_PLMN represents a PLMN in which the UE performs an MDT process, i.e., a PLMN which commands the UE to perform the MDT process, and the MDT process represents a radio network deployment state test process using the MDT scheme.
In the current EPS, the UE does not perform the MDT process if the UE moves to another area not the MDT_PLMN which commands the UE to perform the MDT process. The UE cancels the MDT process result collected through the performance of the MDT process not reporting the MDT process result even if a new PLMN, not the MDT_PLMN commands the UE to perform the MDT process. If one mobile communication service operator uses a plurality of PLMN Identifiers (IDs) for one PLMN, or a plurality of mobile communication service operators interwork and provide a mobile communication service, it is difficult to use an MDT scheme used in the current EPS, and the reason is described follow.
A mobile communication service operator sets a PLMN ID of a PLMN as “A” if the PLMN is used in the 3rd Generation (3 G) mobile communication system, sets the PLMN ID of the PLMN as “B” if the PLMN is used in the 4th Generation (4 G) mobile communication system, so the PLMN can have a plurality of PLMN IDs.
A local mobile communication service operator M which provides a mobile communication service in an area “M” and a local mobile communication service operator N which provides a mobile communication service in an area “N” use different PLMN IDs. If the local mobile communication service operators M and N provide a mobile communication service operator united_mobile communication service, the local mobile communication service operators M and N are united mobile communication service operators, and the united mobile communication service operators provide a mobile communication service using a plurality of PLMN IDs.
As described above, in the current EPS, a UE does not perform an MDT process if the UE moves to another area not an MDT_PLMN which commands the UE to perform the MDT process. The UE cancels an MDT process result collected through the performance of the MDT process not reporting the MDT process result even if a new PLMN, not the MDT_PLMN commands the UE to perform the MDT process. So, there is a need for a method in which a UE performs an MDT process for a PLMN having a plurality of PLMN IDs, and reports an MDT process result to the PLMN.